Influence of Soft Tissue Thickness Upon Dental Implant Esthetics

Overview

Since the beginning of the implant dentistry, a large variety of materials have been used for restoring single or multiple implants, such as gold, titanium, alumina (Al2O3), and zirconia (ZrO2). Patient physical and esthetic requirements play one of the most important role in making decisions related to which material should be chosen. In fact, long-term stability, compatibility with oral tissues esthetics and costs should be considered. Several studies demonstrated that both titanium and zirconia have an excellent biocompatibility and long-term stability even though something could change in terms of esthetic outcomes. Related to esthetics, the color of the peri-implant mucosa is an essential factor that clinicians have to take in to account. Unfortunately, discoloration of peri-implant mucosa sometimes happens. Some authors hypothesized that titanium abutments could provoke a grayish appearance of the mucosa, and, in order to avoid this problem, other authors suggested to perform augmentation of the peri-implant soft tissue thickness in the esthetic area. A study on pig maxillae found that the type of abutment or crown material and the mucosa thickness have significant influences on color changes of the mucosa. Titanium induced the most prominent color change, and, in patients with thinner mucosa, zirconia induced the least noticeable color changes. Nowadays, to reliably evaluate differences in color in implantology, the most used method is spectrophotometry, due to the capacity of detecting even small color differences and due to the higher reproducibility. Several investigations on pig jaws using spectrophotometric measurements were carried out recently, with the aim of investigating the color changes. It was found that generally titanium abutment lead to a more pronounced discoloration; however, gingival thickness greater than 2 mm did not reveal any difference related to the type of abutments. In addition, an increase in mucosal thickness might minimize the discoloration. The only study on human patients revealed that the color of the peri-implant mucosa presents more dark, green and blue components compared to the natural gingiva. Soft tissue thickness appeared a crucial factor with respect to the spectrophotometrically measured degree of peri-implant mucosal discoloration, with a trend for less pronounced discolorations in patients with thick mucosa. Furthermore, the authors found that peri-implant mucosa was on average 0,5-0,7 mm thicker than natural gingiva. However, this study evaluated the thickness of the gingiva by means of CBCT, which could lead to some errors due to the superimposition of the lips and cheeks, as well as the tongue that occupies the most space of the oral cavity. Moreover, esthetics were evaluated by clinicians visually at a specific distance asking them if discoloration was visible or not visible. Furthermore, no questionnaire was given to patients to evaluate esthetics neither discomfort while brushing. Therefore, The objective of this cross-sectional study is to evaluate the influence of gingival thickness (GT) upon mucosal color (MC) around dental implants measured spectrophotometrically. A secondary goal is to evaluate the correlation between mucosal color changes and type of abutment material around dental implants.